Benzyl isocyanide (CAS NO.: ), which is also known as , isocyanomethyl, could be produced through the following synthetic routes.

A. 5-Benzylaminotetrazole (CAS NO.: ). Freshly distilled benzaldehyde (21.2 g, 0.2 mol) is added in one portion to a warm (50°C) solution of 5-aminotetrazole (17.2 g, 0.2 mol) and triethylamine (20.2 g, 0.2 mol) in 100 mL of absolute methanol. After 15 min the reaction mixture is cooled to room temperature, transferred to an autoclave, and hydrogenated with agitation at room temperature over Pd (10%) on carbon (1 g) for 18 hr at 500 psi (pounds per square inch) of hydrogen. The catalyst is removed by filtration and all volatile material is removed at 60°C under aspirator pressure. The gummy tan solid is triturated with 250 mL of hot water. Aqueous 20% HCl is added until pH 3 is reached. The mixture is cooled to room temperature and the solid collected, washed with water, and dried over-night at room temperature under reduced pressure (100 μ); yield: 27.5 g (80%), mp 183.5–185°C (lit.2 mp 183°C).

B. Benzyl isocyanide (CAS NO.: ). In a 500-mL, round-bottomed flask equipped with a magnetic stirring bar and a pressure-equalizing funnel are placed 5-benzylaminotetrazole (10.5 g, 60 mmol), 100 mL of 10% sodium hydroxide solution, and 70 mL of dichloromethane. The mixture is cooled to 0°C and a solution of NaOBr in water (165 mL, 65 mmol) is added with vigorous stirring over a 15-min period. The dichloromethane layer is separated and the aqueous phase extracted with five 50-mL portions of dichloromethane. The combined dichloromethane extracts are dried over anhydrous MgSO₄, the drying agent is removed by filtration, and the dichloromethane is removed by simple distillation. The pressure is then reduced to 20 mm with an aspirator and benzyl isocyanide is distilled at 98–100°C; yield: 5.91 g (84%).

Notice: This preparation should be conducted in an efficient hood because of the obnoxious odor of the isocyanide.